1. Field of the Invention
This invention relates to safety valves, and in particular to valves for exposing to a fluid a probe, such as a coaxial salinity cell employed in measuring the conductivity of a pressurized electrolyte solution.
2. Description of the Prior Art
Conventional coaxial-type valves presently in use with probes, such as salinity cells, typically utilize a gate valve configuration having a rising stem and valve handle. The conventional type of valve presents a number of disadvantages. Conventional gate valves require a significant clearance area for cell withdrawal, and further pose the possibility of crushing the cell or probe in the gate valve when closing the gate. Such valves also require packing and repacking around the rising valve stem to prevent leakage.
In pressurized systems using conventional coaxial valves, there is also a danger that the interior of the valve can be accidentally blown out due to the pressure, creating a hazard to the users. In addition, when the valve is in the open position, it is possible for the operator to inadvertently remove the probe from the valve, resulting in injury to the operator from escaping fluid as well as causing damage to the surrounding locations. Furthermore, it is possible to inadvertently open the valve when the probe is missing, again causing injury and damage. In addition, if left partially open by accident, such a valve remains open similarly resulting in injury and flooding.